Aggregate formation under turbulence: small-scale biophysical interactions driving carbon flux in the ocean

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The process of marine aggregate formation is extremely important to the global carbon cycle since sinking aggregates often dominate the carbon flux from the surface ocean, removing CO2 from active exchange with the atmosphere. Existing models predict that the rate of aggregate formation depends on both particle encounter and coagulation efficiency, but the specific relationships describing the latter's dependence on a range of measurable biological and physical factors are still lacking. In this study, researchers from the University of North Carolina at Chapel Hill will use an interdisciplinary approach to experimentally investigate how aggregate formation varies depending on three factors: 1) production of extracellular polymeric substances, 2) turbulence intensity, and 3) particle size. Results from this study will aid in our understanding of carbon export following phytoplankton blooms, and in predicting carbon cycling in a changing ocean.Broader Impacts: In collaboration with the University of North Carolina (UNC) Baccalaureate Education in Science and Teaching program, one undergraduate student training to become a high school teacher would participate in the study to obtain research experience. At the UNC Science Expo, the proponents plan a presentation to the general public on the importance of marine snow aggregates to global climate change. In addition, they plan a demonstration of their ongoing research project at the Joint Fluids Laboratory to the public, K-12 students, and government officials. One postdoc, one graduate student, and one undergraduate student would be supported and trained as part of this project.